Multiple breadbasket failure

Most cooling events that ALLFED worries about would occur when sunlight is reduced and temperatures quickly plummet. The Chicxulub asteroid impact, which occurred approximately 66 million year ago, is perhaps the most famous global cooling event. During asteroid impact events like Chicxulub, ash and soot would loft into the stratosphere, affecting several continents for up to 10 years. But an asteroid impact isn’t the only, or even the most likely, catastrophic risk that could affect sunlight.

The largest volcanic eruptions on the Volcanic Explosivity Index (VEI), the VEI 7s and greater, have also affected temperatures and global food production. One of the largest known eruptions to impact humans was the most recent supervolcanic eruption of the Toba Caldera Complex, which occurred about 74,000 years ago. 

The VEI 7 eruption of Mount Tambora in Indonesia, in 1815, triggered what would become known as the Year Without a Summer, in 1816. Temperatures plummeted globally, disrupting the monsoon season in Asia for three consecutive years and reducing food production around the world. Food shortages, along with riots, looting, violence, and increased vulnerability to disease, were recorded across Asia, Europe, and North America. The 1991 VEI 6 eruption of Mount Pinatubo was 10 times smaller than the Mount Tambora eruption, but still had a measurable global cooling impact.

However, risk and threat analysts say that the most likely cause of global cooling in the near future may be a regional nuclear war.

Nuclear attacks on cities would loft smoke, soot, and debris into the stratosphere. Climate models show that a regional nuclear war between India and Pakistan, involving approximately 100 nuclear weapons, would block sunlight enough to decrease temperatures by about 1.5 °C (3 °F) for a few years. Such a scenario, with similar drops in temperature, has become known as “nuclear autumn.” Previous work by Physicians for Social Responsibility anticipates that the loss of food resulting from a nuclear autumn could leave one to two billion people without sufficient access to food.

While India and Pakistan currently have comparatively small nuclear arsenals, the United States and Russia each have thousands of nuclear weapons. A large nuclear war between these nations could cause a nuclear winter, in which average global temperatures could drop by about 10 to 20 °C (18 to 36 °F)  for half a decade, and could take more than a decade to fully recover. The direct destruction from the nuclear weapons would be horrific, but the resulting global winter would cause food production to collapse, and this loss of food could kill most people on Earth.

There is also the risk of abrupt natural cooling, such as the Younger Dryas event that occurred about 12,000 years ago. In this event, continental temperatures shifted by as much as 10 °C (18 °F) in a decade. Such a dramatic decrease in temperatures could also reduce global food production by more than 10%.

We refer to catastrophes affecting plant health directly as “agronomic catastrophes.” These could include a superweed, super crop disease, super crop pest, a mass die-off of microorganisms that benefit plants, or rapid pollinator loss (e.g., of bees). Some agronomic catastrophes could occur via a mutation that spreads quickly or via an accidental human introduction, but one of the more catastrophic ways that they could occur might be a terrorist attack. Unless an agronomic catastrophe was triggered by a terrorist attack, it’s unlikely that any of these would occur at a global level. However, depending on where it occurred, it could still spread widely enough to impact some of the world’s large breadbaskets.

One of the greatest risks we face over the next few decades, especially from 2050 onwards, is coincident extreme weather events that could impact agriculture, especially in breadbasket regions of the world. Protracted or repeated droughts, major heat waves, floods, and wildfires could all damage or destroy crops, which would significantly reduce food production and distribution.

A United Kingdom government study predicts an 80% likelihood that a combination of extreme weather events could trigger a 10% global agricultural shortfall within this century. This may seem very high, but it’s based on a simple compounding of a low annual risk—the chance of a minor traffic accident on your street is low on any given day, but very high in your lifetime. Ideally, we want to prevent or avoid threats from occurring, but if that’s not possible, the next best option is to mitigate the impacts of the catastrophe to enable an easier recovery.

Even with food shortages that don’t reach the scale of a global catastrophic risk (GCR), many of the solutions ALLFED advocates for could still be useful in national disasters or isolated regions.